The end of August and early September is the peak time for common heather (Calluna vulgaris) to be flowering in the Highlands, and I usually aim to do a couple of days of photography of this seasonal phenomenon at different locations each year. This summer I decided to make a return visit to the Inchvuilt Wood in Glen Strathfarrar, which I’d first been to in 2012, but hadn’t gone back to since then. So it was that I set off there on the first Sunday in September, hoping to find the heather at its peak of blossom…
Strathfarrar is a long glen and it’s quite a distance to get to Inchvuilt, so I had to resist the temptation to stop at some of my favourite places along the way, especially in the woodland at Culligran. Driving further on, to the Braulen Estate, I came to Loch Beannacharan, where there were stunning reflections in the perfectly still water and I had to stop, to enjoy the beautiful early morning views. In particular, there were some very nice cloud formations mirrored in the loch, which were just begging to be photographed …
The beauty of the scene was marred somewhat by the presence of a number of old stumps of Scots pines (Pinus sylvestris) beside the shore of the loch. They bore evidence of having been cut and illustrated that there must have been much more forest in this part of Strathfarrar in the not too distant past. Such stumps can persist for several decades or even a century after the tree dies, because the resin in the pines’ wood acts as a natural preservative. These ones certainly looked like they’d been dead for quite a long time.
However, there were also signs of hope as I found an abundance of young alder trees (Alnus glutinosa) growing near the edge of the loch. These were clearly being held in check by overgrazing from the red deer (Cervus elaphus) population in the glen, as they were all being kept at the height of the surrounding vegetation and in many cases had spread laterally, because they couldn’t make any vertical growth.
It wouldn’t take much reduction in the grazing pressure to allow some of these alders to grow successfully, and that would be a major step in the restoration of the riparian woodland beside the loch. This habitat is a crucial one, as the leaves from the trees fall in the water and provide food for aquatic invertebrates such as caddisfly and stonefly larvae, and those in turn are food for dragonfly nymphs and fish such as brown trout (Salmo trutta) and Atlantic salmon (Salmo salar).
In fact, just a little further along the shore of the loch there was a small patch of larger trees, including some rowans (Sorbus aucuparia) that were covered in berries. The young alders beside them were larger, and almost above the height that deer could reach, thereby indicating that the balance between excessive herbivory and successful tree regeneration was near the tipping point in favour of the latter in this area.
Looking across the loch to the other side, I could see that there were young downy birches (Betula pubescens) growing successfully just above the shoreline, so that was another positive sign.
I’d noticed in the spring that this was a great year for rowan flowers, so I’d been anticipating that late summer would be an abundant season for rowan berries, and this tree was an excellent example of just that.
Mindful of my intention of getting to Inchvuilt, I drove further west in the glen, and then set out on foot, crossing the Farrar River on a small footbridge and heading up towards the wood. On my way I came upon a patch of bracken (Pteridium aquilinum), and as I reached it, several butterflies took off. Some of them settled again on nearby fronds and I was able to get a closer look, recognising them as the Scotch argus (Erebia aethiops). This is a fairly common species in northwest Scotland and adults are on the wing from late July until early September.
Perhaps fitting for the time of the year, these butterflies looked rather faded in their coloration, and some of them had ragged wing edges – both indicating that they had been adults for some time and perhaps were near the end of their lives.
This species apparently occurs in distinct colonies that can be quite large, and I saw at least a dozen of them in this small patch of bracken.
While I was watching the butterflies, I noticed a number of pale cream shapes on some of the bracken fronds, and on some grass stems in amongst the bracken. I didn’t know what these were, but assumed they must be egg masses of some sort. I wondered if they might be from the Scotch argus butterflies, because their location coincided with where they were? I took a number of photos of the egg masses and then later at home I did some searching on the Internet to see if I could find out what they were from. I quickly discovered they weren’t the eggs of the Scotch argus, as those look completely different. I couldn’t find any likely candidates, so I sent out emails to several of my entomologist contacts to see if they could help. One of those, Graham Rotheray, recognised them as being the massed pupal cocoons of a braconid wasp.
Braconids are parasitoid wasps that lay their eggs in the caterpillars of moths and butterflies. The larvae develop inside their host and then emerge to form the mass of pupal cocoons, which is what I had seen on the bracken and grass stems. Although there was no sign in this instance of what their host had been, I wondered if it was the caterpillars of some of the Scotch argus’s. However, when I suggested that to Roy Leverton, an expert on caterpillars, he said that the caterpillars of the Scotch argus are very small at this time of year, and would not have been able to support a brood of braconid larvae like this. Roy suggested that the brown silver-line moth (Petrophora chlorosata) could possibly have been the host instead, but that is only a speculation, and the identify of the species the braconids used to breed in will have to remain a mystery.
Continuing on, the ground began to rise and I got a good view back eastwards, across Loch a’ Mhuillidh, which lies to the west of Loch Beannacharan. On the far, southeastern side of the loch I could see one of the fenced exclosures established for natural regeneration of the forest in this part of the glen. There were good numbers of young trees, mostly birch, growing successfully there, and the exclosure was also distinctive for the prevalence of heather inside it. In the absence of excessive grazing, the natural ecological process of succession from grassland (the predominant vegetation type in the open areas of this glen and most of the northwest Highlands) to dry heath, typified by common heather, takes place.
After a quick break for lunch, I reached the wood itself, which consists of an extensive stand of old Scots pines (Pinus sylvestris) stretching across the hillside. The western section of the woodland forms part of another exclosure that has been fenced for natural regeneration, but in the eastern part, where I was, deer are still free to roam at will, so there are no young trees and the ground vegetation is largely suppressed to a few inches in height. This was readily apparent in the size of both the heather plants and the blaeberries (Vaccinium myrtillus) amongst the trees.
As soon as I got amongst the pines, I noticed interesting bark patterns on some of them, so I stopped to take a few photographs of those. Pine bark is a favourite subject of mine, and I wrote a blog especially about it last year. On this day, some of the bark was bright reddish-orange, indicating that it had been recently revealed by other outer layers flaking off – over time the exposed bark turns a duller more greyish colour.
I enjoyed looking closely at the bark on several of the pines, as well as the pattern of the lichens growing on them and the way that some heather was flowering next to the trees, with the purple flowers providing a pleasing colour contrast to that of the bark.
While I was looking at the pine trunks, an unusual orange circular shape at the base of one caught my eye. Appearing almost like a target from a sideshow game, I wasn’t sure from a distance what it was – it could almost have been something artificial.
When I reached the tree itself, I saw that it was a fungus, and I suspected immediately that it was the dyer’s mazegill (Phaeolus schweinitzii), a polypore fungus that has been used for a long time as a source of colour for natural dyes. I’ve seen this species on pines in Glen Affric before, but always fruiting on the trunk of the trees, whereas this one was emerging from the roots, right where they joined the tree’s trunk.
Back at home later on, I was able to ascertain to my own satisfaction that this was the correct identification for the fungus, and this was also confirmed by Liz Holden, the mycologist who helps me with fungal IDs. Dyer’s mazegill occurs throughout Europe, Asia and North America and causes stem rot on conifers, including pines. It is unusual amongst polypores for growing out of tree roots – most of the others fruit as brackets on the trunks.
Remembering my original purpose for the day, I saw a bright patch of flowering heather at the base of another pine, so I went to have a closer look.
Unlike the heather elsewhere in the woodland, this patch didn’t appear to have been grazed. This was because it was growing next to the base of a Scots pine which had the upturned root plate of a fallen birch tree next to it, and that made it relatively inaccessible to the deer. It was scenes like this that I had been hoping to encounter on this trip, so I was very pleased to find this beautiful clump of heather in full bloom.
Walking further into the woodland, I came across some other patches of larger heather plants, also similarly in abundant blossom. Their lilac shades made an attractive colour combination with the bracken, which was changing from its summer green hue to its bright yellow of early autumn, before turning brown and dying back in the winter. This is the time of year when I can really appreciate bracken, as it can be very difficult to walk through at its height in the summer, especially when it’s taller than me, and it’s also notorious for harbouring deer ticks.
The bracken here though was quite small in size, most likely because the canopy of the pines above was restricting its growth due to the limited amount of light reaching the forest floor underneath.
The bracken and heather combined to create a colourful understory in the forest, and this was augmented in some areas by blaeberries beginning to change colour as well, especially at the base of some of the Scots pines.
As I continued to walk around amongst the old pines, a small area of bright reddish-orange colour caught my eye on the forest floor. Looking down, I saw it was some small fungi that had emerged from a piece of pine root that was exposed on the ground. The colour was slightly unusual, and I didn’t recognise the species. However when I sent the photos to Liz Holden she replied that they were the yellow stagshorn fungus (Calocera viscosa). I know that species and have photographed it before, but have only seen it when it is yellow. Liz said that it had turned this darker orange colour because it was dry, and had also become somewhat shrivelled for the same reason, which explains why I didn’t recognise it.
In another part of the woodland I was surprised, and delighted, to find a large holly tree (Ilex aquifolium) amongst the pines.
Holly is relatively rare in the native pinewoods, although it was almost certainly more abundant in the past. Despite its prickly leaves, deer find it quite palatable, and it has suffered from overgrazing of its seedlings, which has led to its loss from many woodlands.
Soon afterwards I came upon some downy birches (Betula pubescens) in amongst the pines. They were growing in an area of hummocks, with patches of blaeberries and moss scattered between clumps of heather, making another visually pleasing tableau.
By this time it was late in the afternoon, and I had to begin the long walk back to my car, as there’s a gate across the road at the entrance to Strathfarrar and it would soon be locked for the night.
The midges (Culicoides impunctatus) were also getting quite bad, so I took a quick couple of final images of the heather flowering amongst the trees, and then headed for home – it had been another deeply satisfying day out in the Caledonian Forest.